Hurricane sandy, threatening to blast millions of americans with rain, snow and wicked wind. It's an unprecedented super storm in the offing, and if it happens, it could last for days. Storm, sandy is off the coast of florida, sunday, just off north carolina and then head on into new york on tuesday. Our extreme weather team tracking it all tonight and abc's meteorologist ginger zee starts us off from miami, where they are already seeing signs of what's to come. Ginger? Reporter: Diane, the winds have gusted to 50-plus miles an hour and that beast is still over 300 miles away from south florida. This is just the beginning of our journey with sandy, the hurricane that could become a superstorm. Hurricane sandy, crashing through the caribbean. It exploded in size and strength today as it hit the bahamas, after relentlessly pounding jamaica. The category 2 hurricane blasted out winds of over 110 miles per hour, and unleashed a staggering two feet of rain. Here in florida, it won't be a direct hit, but more of a sideswipe. In schools are cancelled tomorrow as sandy approaches. This is ft. Lauderdale beach and it is usually packed. But the only thing being packed up and locked down are these chairs. They expect up to ten-foot waves and deadly rip currents. But the real danger is farther northwest, when sandy collides with a cold weather system. A merger that could create a superstorm. We donald no't normally see storms end up this way. Reporter: That's why it's been called a billion dollar storm. Capable of causing more imagine than hurricane irene last year. The height of the storm should be tuesday, and it will take its sweet time making an exit. Turning in the atmosphere over the same spots for five or six days. Now, depending on where you live, it may bring up to six inches of rain, 80-mile-per-hour wind gusts, 20 to 30-foot high seas and extreme coastal flooding. It's all during a full moon, too, when tides are even higher. It could even bring half a foot of heavy, wet snow as far inland as ohio. 60% chance that sandy will hit us. Reporter: That's why east coast emergency management teams are gearing up and extra help is being brought in from other states. Emergency officials up and down the east coast are warning people that you can't wait. You have to get your emergency kilts and emergency plans in place now. Diane? Ginger, thank you so much. Now abc's weather editor sam champion is here. Show us these giant forces of nature. Reporter: Superstorm, monster storm. This has three ingredients. First of all, you have sandy, that's number one, the hurricane. Normally need warm, tropical waters to thrive. This one is moving fast and it's dragging the moisture with it. Send ingredient, look at the northern part of the screen, the upper left hand side, that cold air. This is the clash of arctic air and tropical air, together, it's an intense clash that deliver a lot of energy, infusion into that storm. It's no longer a tropical similar at that point, a hybrid. And see that line, the jet It's a ribbon of air that's always flowing, more than 100 miles an hour. That, this time, is curved right over this developing storm so it actually super charges or it's like giving steroids to this storm. It will we have in a monster fashion, with intense winds and rain. And lasting a long time, it could last for days? Reporter: And last for days. One thing we have to watch is where it hits. Right, so, show us the probability as of right now. Reporter: Looking at the spttis, very little for this opportunity to miss everyone completely. The real important part here is, which line this storm will take. If it hits in d.C., Very different conditions. Someone is going to get the worst side of a very bad storm. The thing between now and monday is to watch this very carefully as we are able to pinpoint more closely where this storm lands. All the models show it coming in.

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